Recent progress in microelectronics has greatly miniaturized radio communication devices such as receivers, transmitters and antennas. This miniaturization has permitted the integration of these components into wrist-carried radio devices.
While a number of wrist telephone designs have been explored, none are completely satisfactory. In one design an antenna and loudspeaker are embedded in the wrist strap. The loudspeaker is used also as a microphone, but presumably not at the same time that it is used as a loudspeaker. This type of device, however, lacks privacy because the hearing device is the loud speaker and the volume of the device must be loud because the device is not located near the user's ear. In addition, the battery required to operate the speaker is quite bulky. In another wrist radio device the microphone and speaker are located at the ends of the wrist strap. To use this device, however, the user must remove the device from his wrist and hold one end of the strap in front of his mouth and the other end near his ear. The microphone and speaker must be sufficiently spaced apart to avoid feedback between the components. Another drawback of this device is the tendency to put it down and leave it behind. Yet a third design comprises a wristwatch radio receiver with a receptacle embedded in one strap end for receiving a connection jack for an earphone. However, a separate attachment is needed for the earphone, and this attachment is likely to be lost or misplaced.
Thus there is a need for a practical wrist radiotelephone which can be easily carried on the person, which can permit private conversation, and which is free of easily lost components.